The present invention relates to infrared transmitting films and infrared-sensor covers and infrared-sensor units using same, and more particularly, to the infrared transmitting films and the infrared-sensor covers and infrared-sensor units using same, which are suitable for sensors for sensing a distance to a preceding vehicle such as motor vehicle.
Generally, infrared sensors have been used with transparent or semitransparent infrared transmitting cover. However, such infrared transmitting cover allows a sensor main body to be seen from the outside, leading to possible degradation in design quality. Moreover, if a carbon black or the like for absorbing visible light is contained in the infrared-sensor cover to conceal the sensor main body, the cover can achieve the object of concealment, but loses the transmission-ability for infrared ray.
Moreover, when the infrared sensor is arranged at the back of a radiator grille for, e.g. motor vehicles to measure an inter-vehicle distance, the radiator grille, which forms an obstacle to the infrared sensor, should be eliminated completely or removed partly to secure an optical path of infrared ray.
On the other hand, the radiator grille is an important portion in terms of vehicle design, and therefore requires high design quality. It is a recent tendency to apply plating to the radiator grille to enhance the visual quality. Thus, there is a great demand for infrared-sensor covers having luster or brilliance like plating.
It is, therefore, an object of the present invention to provide infrared transmitting films which allow compatibility between the transmission-ability for infrared ray and the concealment of the infrared-sensor main body, and provide design quality having luster or brilliance like plating. Another object of the present invention is to provide infrared-sensor covers and infrared-sensor units using such infrared transmitting films.
The present invention generally provides a film for transmitting infrared ray, comprising:
a mirror-coat layer comprising a lamination of a first layer and a second layer, the first layer having a refractive index greater than that of the second layer; and
a color-material layer placed on the mirror-coat layer, the color-material layer comprising at least one color material and a binder, wherein the color-material layer absorbs visible light in a given wavelength range and transmits infrared ray,
wherein the film has 80% or more transmission factor for infrared ray.
One aspect of the present invention is to provide a cover for an infrared sensor, comprising:
a base material with transmission-ability for infrared ray; and
a film that transmits infrared ray, the film being disposed adjacent to the base material, the film comprising:
a mirror-coat layer comprising a lamination of a first layer and a second layer, the first layer having a refractive index greater than that of the second layer; and
a color-material layer placed on the mirror-coat layer, the color-material layer comprising at least one color material and a binder, wherein the color-material layer absorbs visible light in a given wavelength range and transmits infrared ray,
wherein the film has 80% or more transmission factor for infrared ray,
wherein the cover has 70% or more transmission factor for infrared ray.
Still another aspect of the present invention is to provide, in an infrared-sensor unit:
a cover, comprising:
a base material with transmission-ability for infrared ray; and
a film that transmits infrared ray, the film being disposed adjacent to the base material, the film comprising:
a mirror-coat layer comprising a lamination of a first layer and a second layer, the first layer having a refractive index greater than that of the second layer; and
a color-material layer placed on the mirror-coat layer, the color-material layer comprising at least one color material and a binder, wherein the color-material layer absorbs visible light in a given wavelength range and transmits infrared ray,
wherein the film has 80% or more transmission factor for infrared ray,
wherein the cover has 70% or more transmission factor for infrared ray.